In the customary polymerization of vinyl monomers, by the emulsion polymerization process, suitable latices have been difficult to obtain since the latices usually contain particles of varying size and are either too fine or too large. In addition to particle size uniformity, other properties of the polymers or resins produced by emulsion polymerization need to be improved, such as plastisol viscosity, clarity, gel temperature, as well as bloom and bleed properties in products made therefrom. Various proposals have heretofore been made to improve these properties with some success but not the ultimate success desired. For example, the use of various different emulsifiers and catalysts have been proposed. Also, varying the conditions of polymerization has been suggested. However, in most of these cases, too much coagulation occurred with the resulting latex containing too much coagulum or partially agglomerated particles which precipitate reducing the yield. Further, the shelflife of such latices leave much to be desired. It is desirable to have latices which change very little during storage with respect to viscosity and have and maintain good heat stability.
Another difficulty in producing vinyl dispersion polymers or resins by means of emulsion polymerization is the large amounts of emulsifier or soap that must be employed. These high levels not only entail high raw material costs, but also put limits on the desirable resin properties which one can attain with the emulsion polymerization procedure. A reduction in the amount of emulsifier or soap needed in the polymerization recipe would be most desirable.
In addition to the above difficulties, a most important problem today is the increasing cost of energy. As a result, there is a great need in the marketplace for a low energy vinyl polymer or resin. By low energy vinyl polymer or resin is meant one that can be processed either at a lower temperature or at a faster speed as compared to those vinyl resins currently available. This is particularly important in the case of the dispersion vinyl resins where a large amount of heat is needed to fuse the plastisols or organosols made therefrom. Accordingly, there is a need in the art for a method of making low fusion dispersion vinyl resins using low emulsifier and which result in improved plastisol properties.